1. Field of the Invention
The present invention relates generally to the art of batteries and more particularly to the art of batteries of the lead-acid variety which include a number of plates in each battery cell, the plates of like polarity being joined to one another by current carrying straps. Still more specifically, the present invention relates to such batteries which have increased plate area and reduced strap height.
2. Description of the Prior Art
The tendency in battery construction in the early 1990's is to have a lower overall battery height. With the increasing use of lower profile batteries and with the advent of immobilized systems, it is important to reduce the head space to the maximum extent possible in designing batteries. A reduction in head space can result in an increase in plate height, thereby increasing the plate surface area. In a most optimum system, it would be desirable to have the plate area increase of the individual plates reach a high enough level so that one or more plates could be dropped from each cell, thereby allowing for wider plates than those used in current battery design.
In immobilized battery systems, the need also exists to reduce the empty space over the top of the plates, commonly referred to as the head space. Numerous attempts have been made to accomplish this objective, all without a desirable level of success.
Several patents disclose systems which incorporate, at first glance, some of the elements of the battery construction of the present invention. For example, in U.S. Pat. No. 1,126,671 issued to Wilson on Jan. 26, 1915 for "Storage Battery", a battery system is described in which two distributing bars are provided at widely spaced apart locations on a positive battery plate. Collector straps are joined to the distributor bars, the straps being separate elements, spaced apart from one another by the collector strap for the negative plates. In the disclosed design, the negative plate has a single distributor bar located at approximately its midpoint. There is no teaching or suggestion in Wilson of using low profile straps to contact plural lugs for the reduction of head space or strap height.
Another system involving a pair of lugs is disclosed in U.S. Pat. No. 1,336,127 issued Apr. 6, 1920 to Carpenter for "Terminal Means For Battery Plates". In this design, a pair of lugs is provided for the battery plates, the lugs extending upwardly and being directed toward one another so that their upper edges are arranged at an angle to one another. A single trapezoidally shaped strap is placed between the lug upper surfaces and is joined thereto by melted lead to complete the connection. There is no indication in the Carpenter patent that the lugs and strap arrangement results in either reduced head space, plate area increase or strap height reduction.
Another patent disclosing two lugs on positive battery plates is U.S. Pat. No. 1,069,809 issued Aug. 12, 1913 to Prince for "Storage Battery". In this construction, the lugs are located at the opposite upper corners of the plate and are located at those locations to equalize current density.
A different multi-lug system is described in U.S. Pat. No. 1,600,083 issued Sep. 14, 1926 to Webster for "Electric Storage Battery". In this design, the original plate is constructed with as many as three lugs, two of which are shown extending upwardly from the top of one plate. However, in this device, the multiple lugs are provided for flexibility in battery design and two of the three described lugs are removed, depending upon which design alternative is selected.
In U.S. Pat. No. 1,947,473 issued Feb. 20, 1934 to Huebner for "Storage Battery", two short lugs extend from the upper portion of the battery, but according to the description only a single lug is used. It is apparent that the grid construction provides one lug which is used with the positive connector strap and a second lug which is used for the negative strap collector.
Yet another patent disclosing a plurality of lugs for a battery grid is U.S. Pat. No. 3,808,054 issued Apr. 30, 1974 to Wheadon, et al for "Wound-Wire Storage Battery Grid". In this patent, continuous lengths of a plurality of wires are formed into grid segments and are wound with one another, with the wires periodically being gathered into lug forming nested loops. The wires extend in a fan-like array therefrom. While the patent is silent with regard to the use of these lugs, it would appear that if two such gathered lugs exist on a single grid, one would be used for attachment of the positive strap and an adjacent plate would employ the other lug for the negative collector strap.
None of the foregoing patents disclose or suggest solutions to the problems discussed initially in this section of the specification. None of the patents indicate that the size of the grid can be expanded by using two lugs connected with collector straps which are joined at a single weld or that the overall height of the straps can be lowered. Moreover, there is no suggestion that using collector straps which are placed over and fused with dual lugs can efficiently reduce vibration failure. A system which overcomes the disadvantages of the prior art and provides the improvements noted in the beginning portion of this section of the specification would represent a significant advance in the art.